The issue of weight management concerns many of the pet owners and veterinarians. Weight can be managed by controlling caloric intake and/or giving significant amount exercise to pets. Caloric intake can be controlled by feeding low calorie pet foods or feeding a smaller amount of regular calorie pet food. Low calorie pet foods achieve low energy density by having increased fiber levels and decreased fat levels in the diets, often resulting in a less palatable food. In addition, because of the high level of fiber in low calorie products, pets consuming this type of food product often produce larger amounts of feces. Also, because pets consume less of this product, owners often feel the need to compensate by feeding more treats to the pet. The treats provide additional calories, resulting in continued weight gain. Furthermore, while compliance with feeding instructions often results in the loss of body weight, there is a risk of losing lean body mass along with loss of body fat.
Another way to reduce the energy density of a food product is to puff the food product to create a less dense food product. Highly expanded puffed human snack foods are known. Such snacks typically have a bulk density of about 48 kg/m3 (about 3 lb/ft3) to about 64 kg/m3 (about 4 lb/ft3) and usually have a very high starch content, with carbohydrates comprising 70-80% by weight. Similarly, puffed breakfast cereals have a bulk density of about 48 kg/m3 (about 3 lb/ft3) to about 225 kg/m3 (about 14 lb/ft3) and also contain about 70-80% by weight carbohydrates, with an amylose to amylopectin ratio of about 25:75. Because of the high starch content, such compositions are not nutritionally complete.
Highly expanded snacks and breakfast cereals having densities of about 48 kg/m3 (about 3 lb/ft3) are generally made with pure starch or whole grain cereals and are coated with flavorings subsequent to puffing. Upon extrusion, pure starch can expand up to 5000% and whole grains (65-78% starch) can expand up to 400%. Pet food blends (40-50% starch) can expand only about 200-300% and oilseeds (0-10% starch) can expand only 150-200%. Animal meal, a main nutritional ingredient of animal meal, is high in protein and is an ingredient that is negative to expansion. Other nutritional ingredients are also negative or neutral to expansion. Thus, in general, more nutritionally complete mixtures have a lower maximum expansion than mixtures high in starch. Moreover, more nutritionally complete compositions that include a higher percentage of protein generally require more extreme extrusion conditions involving greater heat and/or pressure. Such conditions cause some of the starch to degrade. When the starch degrades, the resulting product either fails to puff or collapses upon exiting the extruder.
It has been found that a nutritionally complete mixture containing sufficient concentrations of high amylose starch can withstand the more extreme conditions used to extrude nutritionally complete compositions. Thus, a nutritionally complete composition can be made less dense by puffing the product as it is extruded.